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The HSB/HSL Filter The HSB/HSL Filter In this lesson, we’re going to talk about a feature that Adobe removed from Photo- shop over 20 years ago, and that’s HSB/HSL mode. Adobe replaced these modes with an optional filter that allows us to get that functionality back. This will allow us to create selections and make adjustments to the hue or satu- ration of an image in ways that we couldn’t otherwise do. You will first need to download the free HSB/HSL plug-in from Adobe, and you can find it here: https://helpx.adobe.com/photoshop/kb/optional-file-format-plugins.html On the website listed above, look for the plug-in that contains “HSB HSL.” The HSB/HSL Filter © Ben Willmore, All rights reserved 2 The concept The HSB/HSL filter will allow us to adjust the hue or saturation of an image in a special way. One thing we can do is take all of the less-saturated areas and remove the color completely, leaving only the highly saturated areas still in color. We can use the HSB/HSL Filter to achieve the above result. Here, we took all of the less sat- urated parts of the image and made them completely black and white. When we open an image in Photoshop, it will be in RGB mode, meaning that the image is made out of red, green and blue light. We can view these individu- ally in the Channels panel where each channel will be displayed as a black and white image representing the amount of red, green or blue light. We can take the information available in the Chan- nels panel and apply the HSB/HSL filter to it. With the filter, we can determine what information we’re starting with and what information we want to end up with. Because we just opened the When we open a photo in Photoshop, it will image, we know that we’ll be starting be in RGB mode, meaning that it is made out of red, green and blue light. These three can with RGB set as the input mode. We can be viewed individually in the Channels panel. choose whether we want to end up with HSB or HSL. The HSB/HSL Filter © Ben Willmore, All rights reserved 3 HSB stands for Hue, Saturation and Brightness. HSL stands for Hue, Saturation and Luminosity. If we choose HSB, it’s going to take the channels that used to represent Red, Green and Blue and it’s going to change them so that they in- stead represent Hue, Saturation and Brightness. The Hue channel will try to show us what colors are in the When we run the HSB/HSL filter, we can deter- image and it will do this by display- mine what we’re starting with (RGB) and what we ing shades of gray. Each shade rep- want to end up with (HSB or HSL). resents a different hue. The Saturation channel will show us how saturated the various areas in the image are. Anything that’s black represents an area that has no color. Anything that’s white represents an area that’s as colorful as it could get. The shades of gray are all areas in between. The Brightness channel is showing how bright the different areas of the image are. An area that is black is completely dark and an area that’s white is very bright. When we switch the channels from RGB to HSB, the image will stay in RGB mode but the information stored in the three channels will be the Hue, the Satura- tion and the Lightness. The HSB/HSL Filter © Ben Willmore, All rights reserved 4 Brightness vs. Luminosity As we mentioned above, we have the choice between HSB and HSL. Bright- ness and Luminosity might sound like the same thing (and they are very similar), but there is actually a dif- ference, and you’ll notice that the term Brightness is used in some areas of Photoshop and Luminosity is used in others. Brightness is how the computer describes the colors and Luminosity is how we see the colors with our eyes. For example, with Brightness, it might recog- Brightness is how the comput- nize a bright yellow hue as having maximum bright- er sees color. Here, it renders that yellow as being just as ness, because it’s as bright as the hue can possibly bright as white. Luminosity is get. To our eyes, however, the same yellow hue will how the eye sees color, where look darker than white, and so the Luminosity setting the yellow hue will appear slightly darker than white. will not be at its maximum setting. The HSB/HSL filter is going to change what information is shown in the different channels, but it is going to leave the image in the same mode that it was in before, which was RGB. As a re- sult, the image is going to look really strange because the information that’s in the Channels panel is not rep- resenting what Photoshop thinks it does. What Pho- After running the HSB/HSL filter, the image is going to toshop expects to be in the look strange because different information is being stored Red channel is the part of in the different channels. The HSB/HSL Filter © Ben Willmore, All rights reserved 5 the image made of red light, but what’s actually there is the Hue information. The Saturation information will be stored in the Green channel and the Brightness in- formation will be stored in the Blue channel. We’re not going to pay atten- tion to what the image looks like at this point. We’re in- stead going to use the Chan- nels panel to view the individ- ual channels and either make selections based on them or adjust them. In the video example, we clicked on the Green channel, which con- tains the saturation informa- tion in the image. We want to take any of the more mellow colors in the image and make After running the HSB filter, the Saturation information is them completely black and being stored in the Green channel, and here we are view- ing that channel in the Channels panel. The most colorful white, leaving only the really areas are white and the least colorful areas are black. vibrant areas (like the truck) still in color). To do this, we can make an adjustment to this channel using Curves. When working with Curves, we’ll be using the Channel menu, which includes the options to work on RGB, Red, Green or Blue. Because we used the HSB/HSL fil- ter, these menu items will actually represent, HSB, Hue, Saturation and Brightness (even though they will still read out Red, Green and Blue.) The options in the Channel menu within the Curves dialog will read as Red, Green and Blue, but they will actu- ally mean Hue, Satura- tion and Brightness. The HSB/HSL Filter © Ben Willmore, All rights reserved 6 In the Curves dialog, we’ll set the Channel menu to Green, which in this case, represents the saturation in the image. The areas that appear dark in this channel represent the ar- eas with less saturated colors. The areas that appear bright represent the areas with more saturated colors. We’ll add a point to the curve and drag it all the way down, positioning it on the bottom of the chart and Here, the Green channel (which holds the saturation to the right of all the bars rep- information) is being manipulated to make all of the less-saturated colors completely black and white. resenting the mellow colors. In a regular Curves example, this would force all of those areas to black. In this example, it will force all of those less saturated colors to become completely colorless. In the video example, we can see that the only bright areas left are the truck and the This is a view of the Green channel after we made the sky, which were the areas that Curves adjustment. All of the bright areas are the parts that have a lot of color. originally had a lot of color. Looking back at the image as a whole (all three channels at once), it still looks re- ally wacky and we need to make it look normal. We’ll use the HSB/HSL filter again, changing the mode from HSB back to RGB. Note that the filter needs to be view- ing the full color image, so make sure that the top option in the Channels panel The HSB/HSL Filter © Ben Willmore, All rights reserved 7 (RGB) is selected before running the filter. This will make the image look normal again, and we can see what we accomplished. In the result, the truck and the sky are the only parts of the image in full color. The rest of the image has gone black and white. This is because we were able to make adjustments to the image purely based on saturation (desaturating the more mellow colors). The HSB/HSL filter is being run again, this time converting from HSB back to RGB. In the result, you can see that the vibrant areas are the ones that originally contained a lot of color. Make a selection based on saturation We can use the HSB/HSL filter to help us make certain kinds of selections and then use those selections to make adjustments to the image. In the example im- age, we’re going to make a selection based on saturation.
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